I have an HP E2-9000e AMD & I have tried various install types, bootloaders, kernels, filesystems, frequency scaling governors & settings.
The first time I boot up, normal frequency variation occurs, but on subsequent boots, cpu is locked to lowest frequency (798).
Ondemand, Performance - ignored. Even usb sticks have the same result. If I reformat a partition or usb stick - works - once only.
Used various ScPup64 versions which WORK PERFECTLY on any intel pc. Tried with win10 (fastboot on then off) & without win 10.
This seems to be an AMD problem (never have issues with Intel other than Spectre).
Several internet solutions tried without success. Anyone else had this issue & if so, what did you do?
EDIT: - seems to be a power policy issue - see below.